cobalt

The GTS has a tendency to wonder on rough road surfaces at speeds above 50 mph. It feels as though it is being pulled around by the road surface darting left and right not a significant amount but enough to be annoying. The tires are due to be replaced within the next month or so and a wheel allignment was done within 4k miles. It appears to drive fine on smooth roads. I have noticed the inside of the front tires have worn more than the out but have heard this is relatively common. MY turbo has no problems on these same surfaces and feels much smoother in all aspects.

It has been suggested to me that it may be my ball joints or wheel bearings gone bad. I checked the wheel bearings and ball joints and all appear to be in good working order. No play in either by lifting and rocking the tires. I was informed that they still may be the culprit even though they show no obvious play.

I will be doing the front brakes in the next month or so and was curious if anyone has had similar experiance and what their solution was.

I do admit that at the autocross event the car handled great. No lack of control and very smooth through the transitions. More back end sliding than anything else.

Any input would be appreciated.

WallyP

The most likely problem is that your alignment shop didn't know how to align a 928.

If the car is lifted before or during the alignment process, the toe will be wrong after the car settles (which takes ten miles on rough surfaces, fifty miles on very smooth ones).

Wear on the inner edges is NOT normal, nor is wandering - if the alignment is correct!

cobalt

Thanks Wally. I guess the next move is to replace the tires and have it alligned. if the problem persists then I will look elswhere. The allignment was done by Holbert motors but that was back in 2002 and a lot could have happened in 4k miles by the PO.

GlenL

I'm also wondering if you've got stock or correct offset wheels in the front.

Tires also play a role as the wide, flat, stiff performance tires will pull the car more.

Darting, tramlining or whatever you call it can be caused by a poor alignment. Usually by toe-out. The classic bad alignment is where they lift it first. When it settles the wheels go more toe-in.

Find a place with a Hunter-800 alignment rack. That's a no-lift model. There may be others out there.

cobalt

Thanks Glen,

Stock rims and factory sizes. So that is not the issue. I was going to take it to a local shop called EuroTire. They have done good work for me in the past and host a number of PCA tech sessions. I will inquire to what type of equipment they are useing. The car currently is running Michelin Pilots. they appear to be a good tire for the car. Although I have never used them before and have had nothing else to compare on this car. I have S02's on the turbo and have been relatively pleased with them thus far. I am not sure what to switch to yet or if I should stay with the Michelins.

figgen

May also want to look at the steering rack bushings. The rubber wears allowing the rack to wander a bit.

FBIII

I'll agree with Glen. Replaced a tie rod end once and tried to eyeball the toe in till I got an alignment. Had gross amounts of toe out and the car scatted all over the place.

Bill Ball

To some extent cars with wide performance tires (even stock) will do this - tramlining - even with everything set correctly. If it darts around on flat smooth surfaces, that's another issue. If it seems to follow rain grooves or other irregularities, let me know if you ever completely get rid of it.

Alan

Anthony,
My GTS did this also, had the car 4 wheel aligned at the dealer (and they do know what they are doing there) - it got worse so I took it back and they did the whole thing over - no change.

Turns out it was uneven tire wear from being out of alignment previously - change your tires first see if that helps - before you get realigned. Next time I'm going to change tires with the alignment if I can in any way justify it - it was night and day different. The car was horrible to drive - tramlining all over the place - and pulling at the steering wheel HARD! (I have a feeling you know exactly what I mean).

Alan

cobalt

Alan,
I didn't know how to describe it exactly. But the way you put it seems to sum it up. It can be rather unsettling to drive when it does this. Makes for a nervous ride.

Figgen, the steering rack is new so I think I am OK there.

Bill, I will let you know how it works out.

I guess I need to figure out what tire to go with and then have them replaced and the entire car alligned.

Ron_H

Mine does exactly the opposite: at speeds below 45, it seems to not be possible to keep it in a straight line. Wanders at any road irregularity and almost imperceptibly pulls on the steering wheel, which, when corrected, produce darts in the other direction. To keep in a straight line, I can keep moving the wheel back and forth back and forth back and forth without ever stopping in the center. I have changed the steering rack bushings, the upper control arm bushings, the ball joints, the wheel bearings were adjusted, and it still does it. This is the worst, most un-Porsche steering car I have ever encountered, almost as bad as a Ford Explorer, which will NOT go down the road in a straight line. The last time the car was aligned, I discovered after the alignment that the wheel bearings were loose and a ball joint had been loose but not corrected, and the new tires were wearing on the inside. Finally I replaced those tires and did the alignment again. I also switched from Dunlops to Bridgestone with a slight but noticeable improvement. Now it still does the side to side wandering and refuses to track straightly unlike any Porsche I have ever driven or owned. I though it was a 928 trait until I drove Nicole's car which tracks straight. &$#%@*!! I am about to give up on this POS steering.

Randy V

My initial guess is in line with Bill's - tramlining due to the type of tires.

You're not running Bridgestone SO2s, per chance?

drnick

the inside of the front tyres should NOT wear! the outside shoulder might but only through hard corenering. if the inside is wearing then your alignement is definitely out. my experience with SO2 tyres is that they are very good but MPS2 are better.. finding a good alignement shop is tricky but not impossible.

Ron_H

I claim that the problem is insufficient caster, at least at low speeds. My problem lessens dramatically above 45 mph (73 kph). Of course, above 100 mph, the car settles down solidly "on rails" all day long, so I have been somewhat forgiving of the low speed behavior and the sacrifce of $140 tires at about 1/4 of their life. Even painted lines on the road will cause my wheel to pull in my hand at slow speeds.

Nicole

Ron:

If it makes you feel better, my car still does this to a degree, depending on the road aurface. Maybe you did not encounter a situiation where this would be the case, but it does tramline to a degree.

I have to agree with some previous posters, though, in that both the alignment and the tires play a big role in this. Once the tires are worn unevely, even a good alignment will not minimize the issue.

My car had another weird problem when I bought new tires. First I got Kumho 712, which made the car pull to the right like crazy. Then I went to Yokohamas, which allow it to track straight. The steering rack has been replaced also in the meantime.